Phyllis invested 12000 a portion earning a simple interest r

Phyllis invested $12,000, a portion earning a simple interest rate of 3.25% per year and the rest earning a rate of 3% per year. After one year the total interest earned on these investments was $381.25. How much money did she invest at each rate?

Solution

=> 0.0325x+360-0.03x=$381.25

=>0.0025x=($381.25-$360)=$21.25

=> x=$21.25/0.0025=$8,500

so, invested in 3.25% rate=$8,500

and invested in 3% rate=$(12,000-8,500)=$3,500